\[\ 1,5a^{2}b^{- 3} \cdot 4a^{- 3}b^{4} = 6a^{- 1}b = \frac{6b}{a}\]
\[\ \left( \frac{1}{3}x^{- 1}y^{2} \right)^{- 2}\ = \left( \frac{1}{3} \right)^{- 2} \cdot x^{3}y^{- 4} = \frac{9x^{2}}{y^{4}}\]